Method and apparatus for manufacturing light source

ABSTRACT

An apparatus for manufacturing a light source and a method therefor are provided that enables a high efficient light source to be manufactured even when an optical element whose characteristic significantly varies is used. After maintaining temperatures of a laser device and a wavelength conversion element at a temperature where an output of light emitted from each of the device and the element is equal to or greater than a predetermined rate of the maximum output, the laser device and the wavelength conversion element whose temperatures have been maintained are joined together so that the output of the light emitted from the wavelength conversion element is equal to or greater than a predetermined value.

FIELD OF THE INVENTION

The present invention relates to methods and apparatuses formanufacturing a light source by joining a laser device, such as asemiconductor laser and/or a solid-state laser, to a wavelengthconversion element for converting a wavelength of a laser beam to beemitted from the laser device into another.

BACKGROUND OF THE INVENTION

By causing a laser beam emitted from a laser device to enter awavelength conversion element, the laser beam of a desired wavelengthcan be provided, while the efficiency of a light source is reduced ifsuch optical elements are joined together out of their proper relativeposition. Thus, the two optical elements are joined together after therelative position of the two optical elements has been adjusted to focusthe light beam from the laser device on the wavelength conversionelement.

There generally exist two methods of adjusting the relative position oftwo optical elements: one is called passive alignment, in which therelative position is adjusted with reference to the outer appearances ofthe optical elements or a target mark, or the relative position ismechanically determined by an abutment fit, and the other is calledactive alignment in which emission light from a laser device is causedto enter a wavelength conversion element, an amount of the outgoinglaser light through the wavelength conversion element in operation ismeasured with a power meter or like means measures an amount of emittedlight from the laser device with the wavelength conversion element inoperation, and the position of the laser device or the wavelengthconversion element is adjusted to move it three dimensionally so thatthe measured amount of the outgoing light becomes a maximum.

Of these, a suitable adjustment method is selectively used according tothe circumstances, based on conditions such as functional accuracy inoptical elements that configure a light source, a light output power tobe required by the light source, and the like. An example of the activealignment includes a technique in which optical axes of the two opticalelements are aligned so that the maximum amount of light is achieved bymeasuring an amount of the outgoing light that enters a first opticalelement from a second optical element and propagates within the secondoptical element to be caused to emit from the optical element (refer toJapanese Unexamined Patent Application Publication No. H01-180507, whichhereinafter called Patent Document 1; and Japanese Unexamined PatentApplication Publication No. 2004-109256, which is hereinafter calledPatent Document 2).

Further, because the difference in temperatures between respectivestages retaining the two optical elements causes different amount ofvariation in expansion/contraction of the stages, resulting in theretained optical elements being joined together with their misalignedpositions, there is another example in which the two optical elementsare joined together after the two stages have been heated and maintainedat the same temperature (refer to Japanese Unexamined Patent ApplicationPublication No. 2004-294594, which is hereinafter called Patent Document3).

However, a problem is created in that when the temperatures of theoptical elements are not controlled, as is the case with Patent Document1 and Patent Document 2, or the stages retaining the two opticalelements are heated at the same temperature, as is the case with PatentDocument 3, high efficient light source cannot be provided because theoptical elements is likely to significantly vary its characteristics bytemperature and therefore its positions cannot properly be adjusted.

SUMMARY OF THE INVENTION

The present invention is directed to provide a method of and anapparatus for manufacturing a light source that enables a high efficientlight source to be manufactured even if optical elements are used whosecharacteristics greatly vary depending on the temperature.

A method of and apparatus for manufacturing a light source according tothe present invention is such that after a temperature of a wavelengthconversion element is maintained at a temperature that allows an outputof light emitted from the wavelength conversion element to reaches orexceeds a predetermined rate of the maximum output, the laser device andthe wavelength conversion element are joined so that an output of lightemitted from the wavelength conversion element is equal to or greaterthan a predetermined value.

The present invention provides a high efficient light source because thelaser device and the wavelength conversion element can be joined, withthem maintained at their respective temperatures that cause the lightoutputs to increase. These and other objects of the present inventionwill be better understood by reading the following detailed descriptionin combination with the attached drawings of a preferred embodiment ofthe invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic side view illustrating a light source manufactureapparatus according to Embodiment 1 of the present invention;

FIG. 2 is schematic diagram illustrating a positional relationshipbetween a laser device and a wavelength conversion element retained bythe light source manufacture apparatus according to Embodiment 1 of thepresent invention;

FIG. 3A is a view illustrating X, Y and Z coordinates and movementdirections of a moving stage in the light source manufacture apparatusaccording to Embodiment 1 of the present invention;

FIG. 3B is a perspective schematic diagram illustrating axesconfiguration of the moving stage in the light source manufactureapparatus according to Embodiment 1 of the present invention;

FIG. 4 is a graph illustrating a light output variation due to atemperature variation of a laser device for use in a light source to bemanufactured according to the present invention;

FIG. 5 is a graph illustrating a light output variation due to atemperature variation of a wavelength conversion element for use in alight source to be manufactured according to the present invention;

FIG. 6 is a table illustrating an adjustment process, and apparatusstatuses in its individual processes, in the light source manufactureapparatus according to Embodiment 1 of the present invention;

FIG. 7 is a flow chart illustrating details of pre-processing steps inan alignment process according to Embodiment 1 of the present invention;

FIG. 8 is a flow chart illustrating details of processing steps foradjusting positions in Y, Z, θx and θz directions in the alignmentprocess according to Embodiment 1 of the present invention; and

FIG. 9 is a flow chart illustrating details of processing steps foradjusting positions in X, Y and Ay directions in the alignment processaccording to Embodiment 1 of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1

FIG. 1 is a schematic side view illustrating a light source manufactureapparatus according to Embodiment 1 of the present invention. The lightsource manufacture apparatus shown in FIG. 1 aligns an optical axis ofthe laser device to that of a second harmonic generation element(wavelength conversion element) and then join them together to achieveoptical coupling. Here, the optical coupling refers to a condition inwhich light emitted from the laser device is caused to enter without anyenergy loss the second harmonic generation element. A light sourcemanufactured by the light source manufacture apparatus shown in FIG. 1is used for, e.g., a light source for use in a projection televisionset.

Referring to FIG. 1, the light source manufacture apparatus includes astationary stage 3 that retains the second harmonic generation element(hereinafter called SHG element 1), a moving stage 4 that retains alaser device 2, a temperature controller 5 that controls a temperatureof the moving stage 4 by controlling a temperature regulation mechanism13A, a temperature controller 6 that controls a temperature of thestationary stage 3 by controlling a temperature regulation mechanism13B, a power meter 7 that measures an amount of light emitted from theSHG element 1, a movement controller 8 that controls the movements ofthe temperature controllers 5 and 6 and the moving stage 4 based onsignals from the power meter, a dispenser 11 that applies adhesive to asurface of the laser device 2, and a position change mechanism 12 thatmoves in left-right directions in FIG. 1 along a rail 14 so that a lightentry surface of the SHG element 1 or the dispenser 11 comes in aposition located opposite a light exit surface of the laser device 2.

The stationary stage 3 serves as a second retainer, which is made of ahigh thermal conductive metal material, e.g., copper or aluminum,retains or sucks the SHG element 1 on or to its side. The moving stage 4serving as the first retainer, which is configured to be movable withrespect to the stationary stage fixed to a predetermined place, is madeof a high thermal conductive metal material such as copper or aluminum,and retains or sucks the laser device 2 on or to its upper surface.

The temperature controller 5 controls a temperature of the moving stage4 by controlling a temperature regulation mechanism 13A that is made upof a Peltier device, a cartridge heater and the like. More specifically,the temperature controller 5 detects temperature of the moving stage 4via the temperature regulation mechanism 13A and then maintains thetemperature of the moving stage 4 at a predetermined temperature througha feedback control loop. The temperature controller 6 controls atemperature of the stationary stage 3 by controlling the temperatureregulation mechanism 13B that is made up of the Peltier device, thecartridge heater and the like. More specifically, the temperaturecontroller 6 detects the temperature of the stationary stage 3 via thetemperature regulation mechanism 13B and then maintains the temperatureof the stationary stage 3 at a predetermined temperature through afeedback control loop. Characteristics of the SHG element 1 and thelaser device 2 vary according to the temperature variation, which inturn causes variations of the wavelength, mode and intensitydistribution, etc. of light emitted from such optical elements. Thus,the temperature mechanisms 13A and 13B, controlled by the temperaturecontrollers 5 and 6, adjust the temperatures of the stationary stage 3and the moving stage 4, respectively, to those such that thecharacteristics of the SHG element 1 and the laser device 2 becomefavorable. While the temperature of the stationary stage 3 is actuallydifferent from that of the SHG element 1 and the temperature of themoving stage 4 from that of the laser device 2, their respectivetemperature differences are predetermined by experiments andsimulations, to adjust the temperatures of the respective stages so thatthe respective temperatures of the elements reach a desired temperature.In this way, by adjusting the temperatures of the stationary stage 3 andthe moving stage 4, the temperature controllers 5 and 6 adjust thetemperatures of the SHG element 1 and the laser device 2, respectively.Here, the temperature controller 5 and the temperature regulationmechanism 13A constitute the first temperature retainer, while thetemperature controller 6 and the temperature regulation mechanism 13Bconstitute the second temperature retainer.

The power meter serves as the amount-of-light detector, which isdisposed above a light exit surface of the SHG element 1, and measuresan amount of light to be emitted from the laser device 2, through anoptical waveguide of the SHG element 1, and then emitted from the lightexit surface. The movement controller 8 includes an amount-of-lightprocessor 9 that receives information on the amount of light from thepower meter 7, and a position controller 10 that relatively moves themoving stage 4 retaining the laser device 2 with respect to thestationary stage 3, based upon information on the amount-of-lightinformation delivered from the amount-of-light processor 9. The movementcontroller 8 also controls the temperature controllers 5 and 6.

The dispenser 11 applies an appropriate amount of adhesive, serving as ajoining substance, to a portion where the SHG element 1 and the laserdevice 2 is joined together. The dispenser 11 is a device that appliesbetween the laser device 2 and the SHG element 1 a joining substance forjoining the device 2 and the element 1 together. The dispenser 11 andthe stationary stage 3 are placed together in the position changemechanism 12. The position change mechanism 12, which engages with therail 14, moves in the left-right directions shown in FIG. 1. Theposition change mechanism 12 moves so that the stationary stage 3 comesin a position located above the laser device 2 in the adjustment processof determining positions of the laser device 2 and the SHG element 1,and also moves so that the dispenser 11 comes in a position locatedabove the laser device 2 in the adhering process of properly applyingadhesive to the joining portion of the laser device 2 and the SHGelement 1.

FIG. 2 is schematic diagram illustrating a positional relationshipbetween a laser device 2 and a SHG element 1 with the position changemechanism 12 moved so that the stationary stage 3 comes in a positionlocated above the laser device 2. The laser device 2 is connected to anenergizing mechanism, not shown. Energization of the laser device 2 bythe energizing mechanism causes the laser device 2 to emit light havinga wavelength of λ (lamda) and an amount of light of P1. Here, the laserdevice 2 is configured with an LD module 201 that emits pump light,and/or with a solid-state laser 202 that receives the pump light fromthe LD module 201, to generate a fundamental wave (laser light) of aspecific wavelength, and resonates and amplifies the generatedfundamental wave (laser light) to emit it. The light emitted from thelaser device 2 enters an optical waveguide 1 a formed in the SHG element1, and after resonated and amplified within the optical waveguide 1 a,the light turns out to be a second harmonic wave having one-half thewavelength of the incident light and having an amount of light of P2.

For example, when a light source manufactured using the light sourcemanufacture apparatus according to the present embodiment is employedfor a light source for use in a projection television set, the lightemitted from the laser device 2 is caused to enter the SHG element 1 andthe second harmonic wave having one-half the wavelength of the incidentlight, whereby high output green and blue light sources can be provided.In the present embodiment, a green light source is achieved byproducing, using the SHG element 1, light having a wavelength of 532 nmfrom light of a 1064 nm wavelength emitted from the laser device 2, aswill be described below.

While the dispenser 11 applies the adhesive to a surface locatedopposite the SHG element 1 of the laser device 2, the adhesive will notbe applied to its surface portion, located opposite an incident surface,of the optical wave guide 1 a in order to eliminate an effect of theadhesive on the light. When the laser device 2 and the SHG element 1 arejoined together, the light entry surface of the optical waveguide 1 aand the light exit surface of the laser device 2 face each other with agap between them corresponding to the thickness of the adhesive.

FIG. 3A is a view illustrating X, Y and Z coordinates and movementdirections of the moving stage 4, while FIG. 3B is a perspectiveschematic diagram illustrating the axial configurations of the movingstage 4. Components that are the same as or corresponding to thecomponents in FIG. 1 bear the same numerals, and their description isnot provided herein. Referring to FIG. 3B, the moving stage 4 isconfigured with an X axis stage 21, a Y axis stage 22, a θz stage 23, aθy stage 24, a θx stage 25 and a Z axis stage 26. Each of the stagesconstituting the moving stage 4 corresponds to each of the movementdirections shown in FIG. 3A (X, Y and Z directions, and θx, θy and θzdirections). For example, turning an adjustment knob provided on theside portion of the X axis stage 21 causes the X axis stage 21 to movein the X direction shown in FIG. 3A, so that the laser device 2 moves inthe X direction, accordingly. Upon movement of the θz stage 23, thelaser device 2 rotates about the Z axis shown in FIG. 3A (i.e., rotatesin the θz direction). In this way, the moving stage 4 enables the laserdevice 2 to move in each of the movement directions (X, Y and Zdirections, and θx, θy and θz directions).

FIG. 4 is a graph illustrating a light output variation due to atemperature variation of the laser device 2. Referring to FIG. 4, thehorizontal axis represents a temperature deviation amount (degree C.) ofthe laser device 2 from an optimum temperature that maximizes theoutput, while the vertical axis represents an output ratio of the laserdevice 2 to the output at the optimum temperature. Here, the outputratio at the deviation amount (degree C.) of zero (at the optimumtemperature) is one.

For example, if the laser device 2 including the LD module 201 isapplied to the light source for use in the projection television set,then the laser device is required to emit light at a high output powerand therefore, the LD module 201 self-generates heat. Thus, unless theheat generated from the LD module 201 is removed, the temperature ofdevice elements in the module 201 rises, thereby causing thecharacteristic of light emission to vary. For example, if the elementtemperature varies one degree C., then the output of light that entersthe SHG element from the laser device 2 decreases by about 3% (about 10%decreases by 5 degrees C. deviation) in comparison to the case where thetemperature is adjusted to a proper one, as shown in FIG. 4.

Thus, when the optical axis alignment is made at a temperature where thecharacteristic value varies abruptly, there is a likelihood that alonger time for the optical axis alignment is required because ofgreater variation in measured values with the amount-of-light measuringdevice, or that the optical axis alignment is made under a relativelylow amount of the light. It is therefore preferable that in order tomake correct alignments in the alignment process, the temperature of thelaser device 2 is adjusted to the optimum temperature.

FIG. 5 is a graph illustrating an output variation due to a temperaturevariation of the SHG element 1. Referring to FIG. 5, the horizontal axisrepresents an amount of deviation in temperature (degrees C.) of the SHGelement from its optimum temperature that maximizes the output, whilethe vertical axis represents an output ratio of the SHG element 1 to theoutput at the optimum temperature. Here, the output ratio at the amountof the deviation (degrees C.) of zero (at the optimum temperature) isone.

If the temperature of the SHG element 1 is deviated by two degrees C.from the optimum temperature, for example, then the output of the secondharmonic wave having one-half the wavelength of light emitted from thelaser device 2 is reduced by about 7% (about 30% reduction for adeviation amount by three degrees C.). For example, when adjustments aremade at a temperature that is deviated significantly from the optimumtemperature, such as the temperature where the intensity is at thesecond highest peak (a deviation of 6.5 degrees C.), there is thelikelihood that the desired output of light cannot be achieved andtherefore the optical axis adjustment cannot be made at a properadjustment position. Thus, preferably, the temperature of the SHGelement 1 is adjusted to the optimum temperature.

Next, their operation will be described. FIG. 6 is a table illustratingan adjustment process and apparatus statuses in its individualprocesses, according to Embodiment 1 of the present invention. Referringto FIG. 6, the adjustment process includes (a) alignment process-1, (b)adhesive application process, and (c) alignment process-2.

In the alignment process-1, the position change mechanism 12 is moved sothat the stationary stage 3 comes in a position located above the laserdevice 2. Subsequently, the moving stage 4 is moved by a predetermineddistance for each of the moving axes (X, Y and Z directions, and θx, θyand θz directions), to detect the relative position of the laser device2 and the SHG element 1 where the amount of light becomes a maximum.Here, in the alignment process-1, because it is placed before theadhesive is applied, air occupies the space between the laser device 2and the SHG element 1, and therefore the temperature of the moving stage4 is set to a temperature (T1) where the 1064 nm wavelength light isemitted most intensely, and the temperature of the stationary stage 3 isset to a temperature (T2) where the second harmonic wave having one-halfthe wavelength of the incident light is most efficiently generated. Thisallows detection of the relative position of the laser device 2 and theSHG element 1, where the amount of light becomes a maximum when the airoccupies the space between the laser device 2 and the SHG element 1.Here, T1 represents a temperature of the moving stage 4 (a first targettemperature) determined in advance, by experiments and simulations, suchthat the laser device 2 most intensely emits the 1064 nm wavelengthlight at the temperature when the air occupies the space between thelaser device 2 and the SHG element 1. Furthermore, T2 represents atemperature of the stationary stage 3 (a second target temperature)determined in advance, by experiments and simulations, such that the SHGelement 1 most efficiently generates the second harmonic wave havingone-half the wavelength of the incident light at the temperature whenthe air occupies the space between the laser device 2 and the SHGelement 1.

Upon detection in the alignment process-1 of the relative position ofthe laser device 2 and the SHG element 1, that maximizes the amount oflight, processing will move to the next adhesive application process. Inthe adhesive application process, the position change mechanism 12 isfirst moved so that the dispenser 11 comes in a position located abovethe laser device 2. Upon movement of the position change mechanism 12, aproper amount of the adhesive is applied to the joining portion of thelaser device 2 and the SHG element 1 using the dispenser 11.

After the adhesive is applied, processing moves to the alignmentprocess-2. In the alignment process-2, the position change mechanism 12is moved so that the stationary stage 3 comes in a position locatedabove the laser device 2. Then, the SHG element 1 is first moved to arelative position of the moving stage 4 and the stationary stage 3,which position has been determined to maximizes the amount of lightbefore the adhesive application.

In the alignment process-1, the air occupies all the space between thelaser device 2 and the SHG element 1, while in the alignment process-2,the adhesive partially occupies the space, and therefore, heat transfersbetween the laser device 2 and the SHG element 1 via the adhesive,thereby varying the element or device temperature. Because thetemperature relationship between the laser device 2 and the SHG element1 is thus different from that in the alignment process-1, the relativeposition maximizing the amount of light determined after the adhesiveapplication become different form that determined before the adhesiveapplication, if the temperatures of the laser device 2 and the SHGelement 1 are not properly controlled. It is now known that whenadjustment processes are actually executed at the constant temperaturesfor the respective stages maintained before and after the adhesiveapplication, i.e., with the temperature of each stage in the alignmentprocess-2 being the same as that in the alignment process-1, the amountof light after the adhesive application decreases by about 10%.

To this end, the temperatures of the stationary stage 3 and the movingstage 4 in the alignment process-2 are set to be different values fromthose in the alignment process-1. In this case, the temperature of themoving stage 4 is adjusted, using the temperature controller 5, to atemperature (T3) where the 1064 nm wavelength light is emitted mostintensely, and the temperature of the stationary stage 3 is alsoadjusted to a temperature where the second harmonic wave having one-halfthe wavelength of the incident light is generated most effectively.Here, T3 represents a temperature of the moving stage 4 (the firsttarget temperature) determined in advance, by experiments andsimulations, such that the laser device 2 most intensely emits the 1064nm wavelength light at the temperatures when the adhesive partiallyoccupies the space between the laser device 2 and the SHG element 1.Furthermore, T4 represents a temperature of the stationary stage 3 (asecond target temperature) determined in advance, by experiments andsimulations, such that the SHG element 1 most effectively generates thesecond harmonic wave having one-half the wavelength of the incidentlight at the temperatures when the adhesive partially occupy the spacebetween the laser device 2 and the SHG element 1.

After adjustment of the temperatures of the stationary stage 3 and themoving stage 4, the moving stage is caused to finely move in the sixdirections—X, Y, Z, θx, θy, and θz directions—from the relative positionthat has been determined before the adhesive application and maximizesthe amount of light. A relative position of the laser device 2 and theSHG element 1 is determined where the amount of light of the power meter7 reaches or exceeds a given amount by fine movement, and the element 1and the device 2 are adhesively fixed together at this relativeposition. The temperature control of the laser device 2 and the SHGelement 1 continues until such optical elements are adhesively fixedtogether; after their fixation, the device 2 and element 1, fixedtogether, are removed from the stationary stage 3 and the moving stage4, respectively. Since some adhesive starts hardening in about 120seconds after having been applied, position adjustments of opticalelements in the alignment process-2 needs to be made within such aperiod when using such an adhesive. By keeping the laser device 2energized until the two optical elements are adhesively fixed together,an influence of temperature variation due to deenergization can beeliminated.

The reason that the alignment process-1 and the alignment process-2 areseparately executed is to make correct optical axis alignments even ifthe amount of heat transfer between the optical elements varies beforeand after applying the adhesive. Furthermore, because the adhesiveapplication process is conducted after the alignment process-1, theadhesive application can be made after confirming a proper output ofeach of the elements in the alignment process-1, which eliminates aproblem in the alignment process such that because of one part beingdefective item, the other, albeit non-defective item, cannot beutilized, either. Further, because the adhesive application process isconducted after roughly determining the positions in the alignmentprocess-1, the problem associated with the adhesive squeezing out frombetween the optical elements and flowing toward the surface of theoptical waveguide during the position adjustment process, can also beeliminated. Moreover, because the time required for the optical axisalignment in the alignment process-2 can be made shorter than that inthe alignment process-1, the problem associated with adhesive hardeningdue to a prolonged alignment time can also be resolved.

Next, the alignment process-1 (A in FIG. 6) will be described in moredetail. FIG. 7 is a flow chart illustrating details of pre-processingsteps in the alignment process-1, FIG. 8 is a flow chart illustratingdetails of processing steps of adjusting the positions in the Y, Z, θxand θz directions in the alignment process-1, and FIG. 9 is a flow chartillustrating details of processing steps of adjusting the positions inthe X, Y and θy directions in the alignment process-1. A circled 1 inFIG. 7 corresponds to a circled 1 in FIG. 8, and a circled 2 in FIG. 8to a circled 2 in FIG. 9; that is, FIGS. 7 through 9 constitute one flowchart.

Referring to FIG. 7, the SHG element is first disposed on the stationarystage 3 and the laser device 2 on the moving stage 4 using hands or acarriage mechanism, not shown (S1). Next, the energizing circuitenergizes the laser device 2 (S2). The temperature adjustment of themoving stage 4 is initiated using the temperature controller (S3). Thetemperature adjustment is made in a way such that the temperature of thelaser device 2 reaches a temperature (e.g., 40 degrees C.) where the1064 nm wavelength light is emitted most intensely from the laser device2. The temperature adjustment of the moving stage 4 continues until theSHG element 1 and the laser device 2 are adhesively fixed together. Thetemperature adjustment of the stationary stage 3 is initiated using thetemperature regulation mechanism 6 (S4). The temperature adjustment ismade in a way such that the temperature of the SHG element 1 reaches atemperature (e.g., 70 degrees C.) where the laser device 2 mostefficiently emits the second harmonic wave having one-half thewavelength of the incident light. The temperature control of thestationary stage 3 continues until the SHG element 1 and the laserdevice 2 are adhesively fixed together. With the temperatures of thelaser device 2 and the SHG element 1 adjusted to a proper temperature,the power meter 7 starts measuring the amount of light of the secondharmonic wave emitted from the SHG element 1 (S5). The measurement usingthe power meter 7 continues until the alignment process is completed.

Next, the position controller 10 moves the moving stage 4 based uponinformation on the amount of light from the power meter 7. This movementcan cause the laser device retained by the moving stage 4 to finely movein the six axis directions—X, Y, Z, θx, θy, and θz directions. Referringto FIG. 8, the position controller 10 first adjusts the Y direction andthe θz direction (light waveguide path thick-wise direction) so that thelight emitted from the laser device 2 sufficiently enters the opticalwaveguide 1 a of the SHG element 1 (S6). The adjustments in the Y andthe θz directions are made by causing the moving stage 4 to move in theY and the θz directions by a predetermined range and to come in aposition, within the movement range, where the amount of light reaches amaximum. As a result, if the amount of light measured by the power meter7 reaches or exceeds the predetermined value W1 (“Yes” for S7), then theadjustment is completed for the sufficient amount of light beingproduced (S21), and the movement controller 8 records the relativeposition of the laser device 2 and the SHG element 2. If the amount oflight to be measured using the power meter 7 is smaller than thepredetermined value W2 (“No” in S7), then whether the amount of light tobe measured with the power meter 7 is equal to or greater than thepredetermined value W4 is subsequently determined. If the amount oflight measured therewith is equal to or smaller than the predeterminedvalue W2 (Yes in S8), then the adjustment process is completed for anyone of the elements being defective (S22). Here, the predetermined valueW1 is determined so that the amount of light to be emitted from the SHGelement 1 is equal to or greater than the amount of light required bythe design of the light source. The predetermined value W2 is set to agiven proportion of the maximum amount of light (e.g., 50%). The ratiois determined based on experimentally assessed results.

When the amount of light measured using the power meter 7 is greaterthan the predetermined value W2 (“No” for S8), the adjustments in the Zand the θx directions are made in order to more effectively resonate thelight within the optical waveguide 1 a of the SHG element 1 (S9). Theadjustments in the Z and the θx directions are made by causing themoving stage 4 to move in the Z and the θx directions by a predeterminedrange and to come in a position, within the predetermined range, wherethe amount of light reaches a maximum. Since adjusting the positions inthe Y and θx directions are likely to cause the adjusted position in theY and θz directions to be changed, the positions are readjusted in the Yand the θz directions (S10). The reason that the positions in the Y andθz directions are readjusted is that an effect of the change in the Yand θz directions on the output of light is greater than that in therest of the directions. As a result of readjustments in the Y and θzdirections, if the amount of light measured using the power meter 7reaches or exceeds the predetermined value W1 (“Yes” in S7), then theadjustment is completed for the sufficient amount of light beingproduced (S21), and the movement controller 8 records the relativeposition of the SHG element 1 and the laser device 2. If the amount oflight measured using the power meter 7 is smaller than the predeterminedvalue W2 (“No” in S11), then whether the amount of light to be measuredusing the power meter 7 is equal to or smaller than the predeterminedvalue W4 is subsequently determined. If the amount of light measuredtherewith is equal to or smaller than the predetermined value W2 (“Yes”in S11), then the adjustment process is completed for any one of theelements being defective (S22).

Referring to FIG. 9, when the amount of light measured with the powermeter 7 is greater than the predetermined value W2 (“No” for S11), theadjustments in the X and θy directions are made (S13). The adjustmentsin the Y and the θy directions are made by causing the moving stage 4 tomove in the X and the θx directions by a predetermined range and to comein a position, within the predetermined range, where the amount of lightreaches a maximum. Since adjusting the positions in the Y and θydirections are likely to cause the adjusted position in the Y and θzdirections to be changed, the positions in the Y and the θz directionsare readjusted (S14). As a result of readjustments in the Y and θzdirections, if the amount of light measured using the power meter 7reaches or exceeds the predetermined value W1 (“Yes” in S15), then theadjustment is completed for the sufficient amount of light beingproduced (S21), and the movement controller 8 records the relativeposition of the SHG element 1 and the laser device 2. If the amount oflight measured using the power meter 7 is smaller than the predeterminedvalue W2 (“No” in S15), then the adjustment process is completed for anyone of the elements being defective (S22).

In FIGS. 7 through 9, if the amount of light measured with the powermeter 7 reaches or exceeds the predetermined value W1, then theadjustment is completed for the sufficient amount of light beingproduced (S21), whereby no subsequent adjustment in the X, Z, θx and θydirections is made when the amount of light with the predetermined valueis attained by adjustments in, for instance, the Y and θz directions.The reason for this is to reduce the adjustment period of time. If timepermitted, the alignments may be made for all the axes while the amountof light with the power meter 7 is being observed, to determine therelative position where the light output reaches a maximum.

Further, if the amount of light measured with the power meter 7 is belowthe predetermined value W2 (“Yes” in S8 and S15), then the adjustmentprocess is completed for any one of the elements being defective (S22),and if the amount of light measured using the power meter 7 is below thepredetermined value W2 (“No” in S15), then the adjustment process iscompleted for any one of the elements being defective (S22). In thisway, in situations where the amount of light does not reaches or exceedsa given value even by the adjustment of each movement axis (X, Y, Z, θx,θy or θz direction), any one of the elements can be determined to bedefective before the adhesive application process (B) for applyingadhesive in between the SHG element 1 and the laser device 2. For theSHG element 1 and the laser device 2 by which the amount of light is notabove the given value, the determination of whichever of the opticalelements is found defective can be made by determining whether or notthe amount of light emitted from each optical element reaches or exceedsa certain value. If the SHG element 1 is found defective, the laserdevice 2 can be put again into the alignment process; if the laserdevice 2 is defective, the SHG element 1 can be. Consequently, when oneoptical element is found defective during optical axis alignment orafter the alignment, the other non-defective optical element does notresult in defective item, thus avoiding high-cost SHG element 1 andlaser device 2 from going to waste.

Further, in the alignment process-2 (C for FIG. 6), the stationary stage3 is caused to move to a predetermined position located above the movingstage 4, and the temperature of the moving stage 4 is changed from T1 toT3 while the temperature of the stationary stage 3 is changed from T2 toT4. After waiting until the temperatures of the respective stagesstabilize at T3 and T4, the alignment process is executed by makingadjustments similar to those in the flow chart shown in FIGS. 8 and 9.

The light source manufacturing apparatus according to the presentinvention is configured so that temperature regulation mechanisms forindividually controlling their temperatures are separately provided onthe respective stages that retain and fix the two optical elements foradjusting their optical axes; thus, optical axes alignment can be madeat the respective optimum temperatures of the optical elements, they aretemperature-dependent in wavelength conversion efficiency and the like,such as SHG element 1 and the laser device, and therefore, a highlyefficient optical coupling can be achieved by way of the optical axesalignment (active alignment) with the optical elements regulated intheir respective appropriate temperature where a required opticalcharacteristic is exhibited in the optical axes alignment process by theoptical elements to be aligned.

Further, even if the optical elements are adjusted in their joiningprocess so that the amount of output light reaches its maximum amount, ahigh efficient light source cannot be obtained if each optical elementsignificantly varies its characteristic depending on the temperature andif the temperatures applied to the joining process of the opticalelements are different from those of the optical elements that is inoperation as the light source, despite the positional adjustment of theoptical elements, whereas a high efficient light source can be providedif the optical element are joined together with their temperatures beingmaintained at the temperature of the optical elements that is inoperation as a part of the light source. In this case, if thetemperature of the laser device 2 serving as part of the light source isset to the temperature where the laser device emits the 1064 nmwavelength light most intensely and if the temperature of the SHGelement 1 serving as part of the light source is set to the temperaturewhere the laser device 2 most efficiently emits the second harmonic wavehaving one-half the wavelength of the incident light.

Further, the optical axis alignments are made before the adhesiveapplication and the temperatures and the optical axis positions of theoptical elements are readjusted or realigned after the adhesiveapplication, with reference to the previously adjusted position, so thataccurate optical axis alignment can be made even when the amount of heattransfer between the optical elements varies before and after theadhesive application. When the optical axis alignment is made by firstlyapplying the adhesive, the problem due to variation in the amount ofthermal transfer can be solved; however, there is the possibility ofcausing a problem associated with the adhesive squeezing out frombetween the optical elements and flowing toward the surface of waveguidepath, or with the adhesive hardening when time-consuming optical axisalignments are made.

Further, when a laser device is adjusted that includes the LD module 201as a high output light source such as one for use in the projectiontelevision set, it is important that during the alignment, heatgenerated from the laser device be discharged and its temperature bemaintained at a predetermined value. The reason is that uponenergization of the laser device to emit light, the LD moduleself-generates heat, so that when the heat from the LD module is notdischarged, the element temperature in the module rises, thereby causinga variation in a light emission characteristic. The light sourcemanufacture apparatus according to the present embodiment enables thedischarge of the heat generated by the LD module to thereby achieve anaccurate adjustment, because the temperature controller 5 controls thetemperature regulation mechanism 13A that has cooling capability.

While the temperature of the moving stage 4 is set to a temperaturewhere the 1064 nm wavelength light is emitted most intensely, and thetemperature of the stationary stage 3 is set to a temperature that mostefficiently generates the second harmonic wave having one-half thewavelength of the incident light, the high efficient light source canalso be provided if the respective temperatures are each set to atemperature where the ratio of the output of the intended light to themaximum output is 90% or more (preferably, 95% or more).

Although in the foregoing description the adjustments have been made byretaining the laser device 2 using the moving stage 4 and then byrelatively moving the device 2 with respect to the SHG element 1, theadjustments may be made by retaining the laser device 2 using anymovable means and then relatively moving the element 1 with respect tothe device 2. Moreover, the adjustments may be made by retaining everyone of the optical elements to individual movable means and then movingboth optical elements.

In FIG. 1, because of the SHG element 1 being disposed on the upperportion of the laser device 2, the power meter 7 is placed above thelaser device 2, to measure the amount of light; however, the opticalaxis of the laser device 2 may be laterally oriented, not upwardly.

In addition, while the SHG element 1 is used as the wavelengthconversion element in the foregoing description; however, the inventionis not limited to the element that generates the second harmonic wave,and may be an element that generates the third or fourth harmonic wave.

In the foregoing description, while the temperature of the laser device2 is set to, for instance, 40 degrees C. and that of the SHG element 1to, e.g., 70 degrees C., the temperature may be set according to theproperties of the respective optical elements because an elementtemperature that maximizes the output differs according to the propertyof the optical element. Actually, in the original design phase, it isknown at what temperature level in degree C. the optical elementproduces its maximum output; therefore, an actually set temperature maybe determined by pre-examining a temperature vs. output relationshipmainly in the neighborhood of the known temperature. While the presentinvention has been shown and described with reference to preferredembodiments thereof, it will be understood by those skilled in the artthat various modifications and the like could be made thereto withoutdeparting from the spirit and scope of the invention.

1. A method of manufacturing a light source, comprising: a first temperature maintaining step of maintaining a laser device at a first temperature where an output of light to be emitted from the laser device is equal to or greater than a predetermined rate of the maximum output; a second temperature maintaining step of maintaining a wavelength conversion element at a second temperature where an output of light emitted from the wavelength conversion element is equal to or greater than a predetermined rate of the maximum output, the wavelength conversion element receiving the light from the laser device and emitting the received light therefrom with a wavelength of the received light converted into another one; and a joining step of joining together the laser device maintained at the first temperature and the wavelength conversion element at the second temperature so that an amount of light emitted from wavelength conversion element is equal to or greater than a predetermined value.
 2. The method of manufacturing a light source of claim 1, wherein the first temperature at which the laser device is maintained is corresponding to an operating temperature of the laser device as a part of the light source, and the second temperature at which the wavelength conversion element is maintained is corresponding to an operating temperature of the wavelength changing device as a part of the light source.
 3. The method of manufacturing a light source of claim 1, wherein the joining step includes: A joining substance application step of placing between the laser device and the wavelength conversion element a joining substance for joining them together, a detection step of detecting a relative position of the laser device and the wavelength conversion element where an amount of the light emitted from the wavelength conversion element is equal or greater than the predetermined value, before the application step of placing the joining substance between the laser device and the wavelength conversion element, a moving step of moving, based on the relative position detected in the detection step, the laser device and/or the wavelength conversion element so that the laser device and the wavelength conversion element come in a relative position where an output of the light emitted from the wavelength conversion element is equal to or greater than the predetermined value after the joining substance has been placed between the laser device and the wavelength conversion element, and a maintaining step of maintaining the laser device and the wavelength conversion element at the relative position resulted from moving by the moving step, until the laser device and the waveguide conversion element are joined together by the joining substance.
 4. The method of manufacturing a light source of claim 2, wherein the joining step includes: A joining substance application step of placing between the laser device and the wavelength conversion element a joining substance for joining them together, a detection step of detecting a relative position of the laser device and the wavelength conversion element where an amount of the light emitted from the wavelength conversion element is equal or greater than the predetermined value, before the application step of placing the joining substance between the laser device and the wavelength conversion element, a moving step of moving, based on the relative position detected in the detection step, the laser device and/or the wavelength conversion element so that the laser device and the wavelength conversion element come in a relative position where an output of the light emitted from the wavelength conversion element is equal to or greater than the predetermined value after the joining substance has been placed between the laser device and the wavelength conversion element, and a maintaining step of maintaining the laser device and the wavelength conversion element at the relative position resulted from moving by the moving step, until the laser device and the waveguide conversion element are joined together by the joining substance.
 5. The method of manufacturing a light source of claim 3, wherein the first temperature maintaining step comprises measuring a temperature of a first retainer that retains the laser device, and heating and/or cooling the first retainer so that the temperature of the first retainer becomes a first target temperature determined in advance in order to maximize the output of the light to be emitted from the laser device, wherein the second temperature maintaining step comprises measuring a temperature of a second retainer that retains the laser device, and heating and/or cooling the second retainer so that the temperature of the second retainer becomes a second target temperature determined in advance in order to maximize the output of the light to be emitted from the wavelength conversion element, and wherein the values of the first target temperature and the second target temperatures in the detection step are different from those in the moving step, respectively.
 6. The method of manufacturing a light source of claim 4, wherein the first temperature maintaining step comprises measuring a temperature of a first retainer that retains the laser device, and heating and/or cooling the first retainer so that the temperature of the first retainer becomes a first target temperature determined in advance in order to maximize the output of the light to be emitted from the laser device, wherein the second temperature maintaining step comprises measuring a temperature of a second retainer that retains the laser device, and heating and/or cooling the second retainer so that the temperature of the second retainer becomes a second target temperature determined in advance in order to maximize the output of the light to be emitted from the wavelength conversion element, and wherein the values of the first target temperature and the second target temperatures in the detection step are different from those in the moving step, respectively.
 7. An apparatus for manufacturing a light source, comprising: a first retainer that retains the laser device; a second retainer that retains a wavelength conversion element that receives the light emitted from the laser device and emits the received light with a wavelength of the received converted light into another one; a first temperature maintainer that maintains the laser device at a temperature where an output of light to be emitted from the laser device is equal to or greater than a predetermined rate of its maximum output; a second temperature maintainer that maintains the wavelength conversion element at a temperature where an output of light to be emitted from the laser device is equal to or greater than a predetermined rate of its maximum output; an amount-of-light detector that measures an amount of light emitted from the wavelength conversion element whose temperature is maintained by the second temperature maintainer, and a position controller that causes the first retainer to move relative to the second retainer and/or causes second retainer to move relative to the first retainer, so that the amount of light measured by the amount-of-light detector reaches or exceeds a predetermined value, and then to join them together, wherein the laser device maintained at the first temperature and the wavelength conversion element maintained at the second temperature are to be joined together so that the amount of light measured by the amount-of-light detector is equal to or greater than a predetermined value.
 8. The method of manufacturing a light source of claim 7, wherein the first temperature at which the laser device is maintained is corresponding to an operating temperature of the laser device as a part of the light source, and the second temperature at which the wavelength conversion element is maintained is corresponding to an operating temperature of the wavelength changing device as a part of the light source.
 9. The apparatus for manufacturing a light source of claim 7, further comprising: a joining substance applicator that places between the laser device and the wavelength conversion element a joining substance for joining them together, wherein the position controller moves the laser device and the wavelength conversion element in a way such that the laser device and the wavelength conversion element come in a relative position where an amount of light measured by the amount-of-light detector is equal to or greater than the predetermined value, before and after the joining substance is placed between the laser device and the wavelength conversion element by the joining substance applicator, and the first and the second retainers retain the laser device and the wavelength conversion element until the laser device and the wavelength conversion element are joined together by the joining substance.
 10. The apparatus for manufacturing a light source of claim 8, further comprising: a joining substance applicator that places between the laser device and the wavelength conversion element a joining substance for joining them together, wherein the position controller moves the laser device and the wavelength conversion element in a way such that the laser device and the wavelength conversion element come in a relative position where an amount of light measured by the amount-of-light detector is equal to or greater than the predetermined value, before and after the joining substance is placed between the laser device and the wavelength conversion element by the joining substance applicator, and the first and the second retainers retain the laser device and the wavelength conversion element until the laser device and the wavelength conversion element are joined together by the joining substance.
 11. The light source manufacture apparatus of claim 9, wherein the first temperature maintainer includes a first temperature conditioner that measures a temperature of the first retainer and heats and/or cools the first retainer, and a first temperature controller that controls the first temperature conditioner so that the temperature of the first retainer becomes a first target temperature determined in advance in order to maximize the output of the light to be emitted from the laser device, and wherein the second temperature maintainer includes a second temperature conditioner that measures a temperature of the second retainer and heats and/or cools the second retainer, and a second temperature controller that controls the second temperature conditioner so that the temperature of the second retainer becomes a second target temperature determined in advance in order to maximize the output of the light to be emitted from the wavelength conversion element, and wherein the values of the first target temperature and the second target temperatures before the joining substance is placed between the laser device and the wavelength conversion element are different from those after the joining substance is placed therebetween, respectively.
 12. The light source manufacture apparatus of claim 10, wherein the first temperature maintainer includes a first temperature conditioner that measures a temperature of the first retainer and heats and/or cools the first retainer, and a first temperature controller that controls the first temperature conditioner so that the temperature of the first retainer becomes a first target temperature determined in advance in order to maximize the output of the light to be emitted from the laser device, and wherein the second temperature maintainer includes a second temperature conditioner that measures a temperature of the second retainer and heats and/or cools the second retainer, and a second temperature controller that controls the second temperature conditioner so that the temperature of the second retainer becomes a second target temperature determined in advance in order to maximize the output of the light to be emitted from the wavelength conversion element, and wherein the values of the first target temperature and the second target temperatures before the joining substance is placed between the laser device and the wavelength conversion element are different from those after the joining substance is placed therebetween, respectively. 